type DiscordMentionAliasesConfig = Record<string, string>;

const MARKDOWN_CODE_SEGMENT_PATTERN = /```[\s\S]*?```|`[^`\n]*`/g;

const MENTION_CANDIDATE_PATTERN = /(^|[\s([{"'.,;:!?])@([a-z0-9_.-]{2,32}(?:#[0-9]{4})?)/gi;

const DISCORD_RESERVED_MENTIONS = new Set(["everyone", "here"]);

const DISCORD_DISCRIMINATOR_SUFFIX = /#\d{4}$/;

});

}

function countBacktickRun(text: string, index: number): number {

let cursor = index;

while (text[cursor] === "`") {

cursor += 1;

}

return cursor - index;

}

function findSameLineBacktickRun(

text: string,

startIndex: number,

runLength: number,

): number | null {

const delimiter = "`".repeat(runLength);

const newlineIndex = text.indexOf("\n", startIndex);

const lineEnd = newlineIndex === -1 ? text.length : newlineIndex;

const closeIndex = text.indexOf(delimiter, startIndex);

return closeIndex !== -1 && closeIndex < lineEnd ? closeIndex + runLength : null;

}

function findFenceEnd(text: string, startIndex: number, runLength: number): number {

let searchIndex = startIndex + runLength;

while (searchIndex < text.length) {

const newlineIndex = text.indexOf("\n", searchIndex);

if (newlineIndex === -1) {

return text.length;

}

let lineCursor = newlineIndex + 1;

while (text[lineCursor] === " " && lineCursor - newlineIndex <= 3) {

lineCursor += 1;

}

const closingRunLength = countBacktickRun(text, lineCursor);

if (closingRunLength >= runLength) {

return lineCursor + closingRunLength;

}

searchIndex = lineCursor + Math.max(closingRunLength, 1);

}

return text.length;

}

function findNextMarkdownCodeSegment(

text: string,

startIndex: number,

): { startIndex: number; endIndex: number } | null {

let searchIndex = startIndex;

while (searchIndex < text.length) {

const segmentStart = text.indexOf("`", searchIndex);

if (segmentStart === -1) {

return null;

}

const runLength = countBacktickRun(text, segmentStart);

const inlineEndIndex = findSameLineBacktickRun(text, segmentStart + runLength, runLength);

if (inlineEndIndex !== null) {

return { startIndex: segmentStart, endIndex: inlineEndIndex };

}

if (runLength >= 3) {

return {

startIndex: segmentStart,

endIndex: findFenceEnd(text, segmentStart, runLength),

};

}

searchIndex = segmentStart + runLength;

}

return null;

}

export function rewriteDiscordKnownMentions(

text: string,

params: {

}

let rewritten = "";

let offset = 0;

MARKDOWN_CODE_SEGMENT_PATTERN.lastIndex = 0;

for (const match of text.matchAll(MARKDOWN_CODE_SEGMENT_PATTERN)) {

const matchIndex = match.index ?? 0;

rewritten += rewritePlainTextMentions(text.slice(offset, matchIndex), params);

rewritten += match[0];

offset = matchIndex + match[0].length;

let segment = findNextMarkdownCodeSegment(text, offset);

while (segment) {

rewritten += rewritePlainTextMentions(text.slice(offset, segment.startIndex), params);

rewritten += text.slice(segment.startIndex, segment.endIndex);

offset = segment.endIndex;

segment = findNextMarkdownCodeSegment(text, offset);

}

rewritten += rewritePlainTextMentions(text.slice(offset), params);

return rewritten;